Question: What is the greatest common factor of $12$ and $18$ ? Another way to say this is: $\operatorname{gcf}(12, 18) = {?}$
Solution: The greatest common factor is the largest number that is a factor of both $12$ and $18$ The factors of $12$ are $1$ $2$ $3$ $4$ $6$ , and $12$ The factors of $18$ are $1$ $2$ $3$ $6$ $9$ , and $18$ Thus, the greatest common factor of $12$ and $18$ is $6$. $\operatorname{gcf}(12, 18) = 6$